“Burn-in” is a test procedure commonly applied to integrated circuit (IC) devices in which the devices are exercised at elevated temperature to determine whether defects are present in the devices. Typically, burn-in is applied only to a sample of a lot of devices that have just been manufactured. In conventional burn-in techniques, each device to be burned-in (sometimes referred to as a “device under test” or “DUT”) is installed in a socket in a burn-in board. A typical burn-in board may have 15 or more sockets, each containing a DUT during the burn-in.
Once the DUTs have been installed in the sockets of the burn-in board, the burn-in board is placed in an oven, typically in company with other burn-in boards having installed therein other DUTs of the sample of devices being burned-in. The oven is then heated to the target burn-in temperature (e.g., 100° C.) and patterns of drive signals are applied to the DUTs via the burn-in boards during the burn-in period (of, e.g., 30 minutes). The DUTs are monitored during the burn-in and/or tested after burn-in to determine whether the DUTs have failed during burn-in. After the burn-in period is complete, the oven is allowed to cool to room temperature, and the burn-in boards are then removed from the oven. Thereafter, the DUTs are de-installed from the sockets of the burn-in boards, and passed to the next stage of test/manufacture.
Because of cycle time required for populating burn-in boards with DUTs and removing the DUTs from the burn-in boards, loading and unloading burn-in boards to/from the oven, and heating and cooling of the oven, the actual elapsed time to provide a 30 minute burn-in may be several hours. Also, burn-in ovens may occupy a substantial amount of factory floor space.
To overcome these and other disadvantages of conventional burn-in, the present inventor, with another, proposed a “self-heating burn-in” procedure in which the heating of the DUTs from room temperature to the target burn-in temperature results entirely from electrical power dissipation within the DUTs themselves. In other words, no oven is required for “self-heating burn-in”. The present inventor has now recognized possible improvements in self-heating burn-in procedures.